The Los Angeles Times reports Tuesday that the operator of the Fukushima nuclear plant, which was damaged by the earthquake and tsunami that hit Japan, has found radioactive iodine in seawater samples 7.5 million times the legal limit. The samples were taken near the plant.

The Japanese government then imposed a new radioactivity limit for fish.

The newspaper reported:

The reading of iodine-131 was recorded Saturday, Tokyo Electric Power Co. said. Another sample taken Monday found the level to be 5 million times the legal limit. The Monday samples also were found to contain radioactive cesium at 1.1 million times the legal limit.

The exact source of the radiation was not immediately clear, though Tepco has said that highly contaminated water has been leaking from a pit near the No. 2 reactor. The utility initially believed that the leak was coming from a crack, but several attempts to seal the crack failed.

On Tuesday the company said the leak instead might be coming from a faulty joint where the pit meets a duct, allowing radioactive water to seep into a layer of gravel underneath. The utility said it would inject “liquid glass” into gravel in an effort to stop further leakage.

Meanwhile, Tepco continued releasing what it described as water contaminated with low levels of radiation into the sea to make room in on-site storage tanks for more highly contaminated water. In all, the company said it planned to release 11,500 tons of the water, but by Tuesday morning it had released less than 25% of that amount.